The introduction of the compact digital audio disc (CD) has resulted in a true advance in audio program playback technology. The compact disc contains a digitally encoded rendering of the program audio signal transferred onto a disc of polycarbonate plastic by molding or stamping. The encoded surface is then uniformly coated with aluminum and coated with a sealant such as lacquer. The aluminum sputtering on the stamped surface creates a reflective surface which is read by a laser beam through the opposite side of the polycarbonate disc. The laser reflection is converted to an audio signal which is heard through standard audio playback components.
The compact disc is considered a substantial advance over the vinyl record album for several reasons. First, the CD is capable of storing considerably more audio program material per unit area than a vinyl album. This permits the use of a much smaller disc for the presentation of recorded music (hence the term "compact" disc). Next, the ability to retain an audio program capable of being digitally decoded results in a substantial improvement in signal to noise ratio and program fidelity when compared with a vinyl record. Finally, the use of a laser beam as the transducer results in little if any degradation of the compact disc playing surface during playback. The playback properties of the compact disc will thus remain essentially unchanged, even after extensive use. However, there are factors which interfere with the reflection of the laser beam from the aluminum sputtered surface and adversely affect CD playback performance. Several such factors are scratches, dust, and fingerprints.
Because of the need to protect the surface of the compact disc through which the laser reflects, i.e., the optical surface, various compact disc storage devices have been developed. By far the most prevalent storage device is a package known as the jewel box. The jewel box consists of two pieces of molded polycarbonate which are hinged along a common side to permit the opening of the box as one would open a book. Snap fit inside one of the polycarbonate pieces is a styrene tray with a center hub which engages the center aperture of the compact disc. The jewel box is slightly larger than the 4.7" diameter of the compact disc. Though the jewel box serves to protect the compact disc, the box itself suffers from certain disadvantages. The box is difficult to open, and it is difficult to remove the compact disc from the centered hub without bending the compact disc. The jewel box is relatively fragile, resulting in breakage of the hinges or the polycarbonate pieces themselves when accidentally dropped. Finally, the jewel box is expensive to manufacture because of the three piece construction and the need to manually assemble the parts.
One alternative to the jewel box for use in after market storage of the compact disc is a device known as the CD Jockee produced by DataPax, Kennewick, Washington. The CD Jockee is a compact disc carrying case which opens into an A-frame shape and has eight two sided, clear vinyl pockets that can carry up to 16 compact discs. The pockets are connected in an overlapping fashion, such that only a small portion of the discs underlying the top disc can be seen. The individual pockets have a clear vinyl front to permit viewing of the side of the compact disc containing identifying printing, and a velour back which contacts the optical surface of the compact disc. The reverse side of each pocket can hold the printed graphics accompanying the compact disc stored on the front, or alternatively it may be used to store another compact disc. The CD Jockee has the disadvantages that when the compact discs are displayed, the discs themselves are exposed to dust because of the open top access to the discs. Further when displayed, one must typically flip through each pocket to find the desired compact disc because only a small portion of the printed surfaces are visible. Also, the velour surfaces generate relatively large amounts of lint which can accumulate on the optical surfaces of the discs.